ACS Flashcards
ACS - definition
Refers to a spectrum of acute myocardial ischaemia and/or infarction. Decreased blood flow in the coronary arteries such that part of the heart muscle is unable to function properly or dies. 3 conditions: - unstable angina - NSTEMI - STEMI
Stable vs Unstable Angina
- Stable angina = at least 70% stenosis; chest pain only on exertion (supplies tissue at rest but heart needs to work harder on exertion) - Unstable angina = usually rupture of plaque with thrombosis -> subendocardial ischaemia. Pain at REST
ACS - cardiac tissue involvement
- UA = subendocardial ischaemia - NSTEMI = subendocardial infarction (20-40 min after onset) - STEMI = transmural infaction (3-6 h after onset)
Cardiac biomarkers and ECG changes
UA - no changes in cardiac markers - ECG may be normal or have changes (ST depression, T wave inversion NSTEMI - elevated cardiac markers - ECG changes: ST depression, T wave inversion STEMI - elevated cardiac biomarkers - ECG changes: ST elevation of at least 1 mm in 2 or more contiguous leads, may have new LBBB or pathological Q waves
Cardiac biomarkers in ACS
- Troponins (I and T): increase 3-12h from onset, peak at about 24-48 h and overall last 10-14 days - CK-MB: rises after 3 h, peaks at about 24 h and lasts up to 72 h (more useful to determine re-infarction) - myoglobin: first one to rise so useful for rapid Dx
ACS - risk factors
- Increasing age - Gender (male for STEMI, female for UA) - Diabetes - Smoking - Hypertension - Hx of coronary artery disease - Hyperlipidaemia - PVD - CKD - Obesity - Inflammatory conditions e.g. RA
What is type 2 MI and some causes?
MI not due to atheroma - Supply and demand mismatch – cardiac muscle not receiving enough oxygen, often due to subendothelial tissue hypoxia – better prognosis than type 1 MI. Causes: - Anaemia - Hypoxia - Shock - Tachyarrhythmia - Bradyarrhythmia
What is type 3 MI?
Type 3 MI: sudden cardiac death due to thromboembolism (no time to measure cardiac enzyme therefore classified as type 3 MI as unknown if they had previous atheroma)
UA - presentation
- increasing frequency of chest pain (several times a day, instead of occasionally) - increasing severity of chest pain (decreasing levels of activity needed to trigger pain and may occur at rest) - retrosternal pressure or heaviness radiating to jaw, arm, or neck that is improved by nitrates - dyspnoea - 4th heart sound (Indicates reduced myocardial relaxation due to ischaemia)
Acute MI - presentation
- central crushing chest pain (sensation of tightness, heaviness, aching, burning, pressure, or squeezing) - diaphoresis, pallor - dyspnoea - N and/or V - dizziness or light-headedness - weakness and anxious - tachycardia - may have S3 or S4 heart sounds
Rarer causes of MI
- Aortic dissection – tearing pain that radiates to the back, different bp in the different arms, widening of mediastinum, risk of pericardial effusion and tamponade - Coronary artery spasm - Oesophageal rupture - Pericarditis – saddle shaped ST elevation
ACS - investigations
- ECG - cardiac biomarkers (tropinin, CK-MB +/- myoglobin) - FBC (normal or low Hb) - U+Es / electrolytes (usually normal) - blood glucose - lipid profile (normal or high total cholesterol and LDL) - coagulation profile (should be normal) - CXR (excludes HF, PE, aortic dissection, etc) - consider echo (regional wall motion abnormalities)
ACS - criteria for hospital admission
Suspected acute coronary syndrome (ACS), who: - Have current chest pain - Have signs of complications (such as PE) - Are pain-free, but have had chest pain in the last 12 hours and have an abnormal ECG - A recent history of ACS, and they develop further chest pain.
Stable angina - treatment (not ACS)
- GTN spray (for use before performing activities known to cause symptoms of angina) - BB or CCB OR either one of: a long-acting nitrate (isosorbide mononitrate) Nicorandil Ivabradine Ranolazine - antiplatelet treatment (low dose aspirin - 75 mg daily) - statins
What to give to people with angina and: 1. stroke 2. diabetes
STROKE clopidogrel instead of aspirin (long term ischaemic stroke Rx also includes warfarin) DIABETES consider adding ACEi